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1NAME 1NAME
2 IO::AIO - Asynchronous Input/Output 2 IO::AIO - Asynchronous/Advanced Input/Output
3 3
4SYNOPSIS 4SYNOPSIS
5 use IO::AIO; 5 use IO::AIO;
6 6
7 aio_open "/etc/passwd", O_RDONLY, 0, sub { 7 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8 my $fh = shift 8 my $fh = shift
9 or die "/etc/passwd: $!"; 9 or die "/etc/passwd: $!";
10 ... 10 ...
11 }; 11 };
12 12
… …
23 my $req = aio_unlink "/tmp/file", sub { }; 23 my $req = aio_unlink "/tmp/file", sub { };
24 $req->cancel; # cancel request if still in queue 24 $req->cancel; # cancel request if still in queue
25 25
26 my $grp = aio_group sub { print "all stats done\n" }; 26 my $grp = aio_group sub { print "all stats done\n" };
27 add $grp aio_stat "..." for ...; 27 add $grp aio_stat "..." for ...;
28
29 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30 use AnyEvent::AIO;
31
32 # EV integration
33 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
34
35 # Event integration
36 Event->io (fd => IO::AIO::poll_fileno,
37 poll => 'r',
38 cb => \&IO::AIO::poll_cb);
39
40 # Glib/Gtk2 integration
41 add_watch Glib::IO IO::AIO::poll_fileno,
42 in => sub { IO::AIO::poll_cb; 1 };
43
44 # Tk integration
45 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46 readable => \&IO::AIO::poll_cb);
47
48 # Danga::Socket integration
49 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50 \&IO::AIO::poll_cb);
51 28
52DESCRIPTION 29DESCRIPTION
53 This module implements asynchronous I/O using whatever means your 30 This module implements asynchronous I/O using whatever means your
54 operating system supports. It is implemented as an interface to "libeio" 31 operating system supports. It is implemented as an interface to "libeio"
55 (<http://software.schmorp.de/pkg/libeio.html>). 32 (<http://software.schmorp.de/pkg/libeio.html>).
… …
78 not well-supported or restricted (GNU/Linux doesn't allow them on normal 55 not well-supported or restricted (GNU/Linux doesn't allow them on normal
79 files currently, for example), and they would only support aio_read and 56 files currently, for example), and they would only support aio_read and
80 aio_write, so the remaining functionality would have to be implemented 57 aio_write, so the remaining functionality would have to be implemented
81 using threads anyway. 58 using threads anyway.
82 59
60 In addition to asynchronous I/O, this module also exports some rather
61 arcane interfaces, such as "madvise" or linux's "splice" system call,
62 which is why the "A" in "AIO" can also mean *advanced*.
63
83 Although the module will work in the presence of other (Perl-) threads, 64 Although the module will work in the presence of other (Perl-) threads,
84 it is currently not reentrant in any way, so use appropriate locking 65 it is currently not reentrant in any way, so use appropriate locking
85 yourself, always call "poll_cb" from within the same thread, or never 66 yourself, always call "poll_cb" from within the same thread, or never
86 call "poll_cb" (or other "aio_" functions) recursively. 67 call "poll_cb" (or other "aio_" functions) recursively.
87 68
88 EXAMPLE 69 EXAMPLE
89 This is a simple example that uses the EV module and loads /etc/passwd 70 This is a simple example that uses the EV module and loads /etc/passwd
90 asynchronously: 71 asynchronously:
91 72
92 use Fcntl;
93 use EV; 73 use EV;
94 use IO::AIO; 74 use IO::AIO;
95 75
96 # register the IO::AIO callback with EV 76 # register the IO::AIO callback with EV
97 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; 77 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98 78
99 # queue the request to open /etc/passwd 79 # queue the request to open /etc/passwd
100 aio_open "/etc/passwd", O_RDONLY, 0, sub { 80 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101 my $fh = shift 81 my $fh = shift
102 or die "error while opening: $!"; 82 or die "error while opening: $!";
103 83
104 # stat'ing filehandles is generally non-blocking 84 # stat'ing filehandles is generally non-blocking
105 my $size = -s $fh; 85 my $size = -s $fh;
… …
114 94
115 # file contents now in $contents 95 # file contents now in $contents
116 print $contents; 96 print $contents;
117 97
118 # exit event loop and program 98 # exit event loop and program
119 EV::unloop; 99 EV::break;
120 }; 100 };
121 }; 101 };
122 102
123 # possibly queue up other requests, or open GUI windows, 103 # possibly queue up other requests, or open GUI windows,
124 # check for sockets etc. etc. 104 # check for sockets etc. etc.
125 105
126 # process events as long as there are some: 106 # process events as long as there are some:
127 EV::loop; 107 EV::run;
128 108
129REQUEST ANATOMY AND LIFETIME 109REQUEST ANATOMY AND LIFETIME
130 Every "aio_*" function creates a request. which is a C data structure 110 Every "aio_*" function creates a request. which is a C data structure
131 not directly visible to Perl. 111 not directly visible to Perl.
132 112
… …
168 anymore (except possibly for the Perl object, but its connection to 148 anymore (except possibly for the Perl object, but its connection to
169 the actual aio request is severed and calling its methods will 149 the actual aio request is severed and calling its methods will
170 either do nothing or result in a runtime error). 150 either do nothing or result in a runtime error).
171 151
172FUNCTIONS 152FUNCTIONS
173 AIO REQUEST FUNCTIONS 153 QUICK OVERVIEW
154 This section simply lists the prototypes most of the functions for quick
155 reference. See the following sections for function-by-function
156 documentation.
157
158 aio_wd $pathname, $callback->($wd)
159 aio_open $pathname, $flags, $mode, $callback->($fh)
160 aio_close $fh, $callback->($status)
161 aio_seek $fh,$offset,$whence, $callback->($offs)
162 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
163 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
164 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
165 aio_readahead $fh,$offset,$length, $callback->($retval)
166 aio_stat $fh_or_path, $callback->($status)
167 aio_lstat $fh, $callback->($status)
168 aio_statvfs $fh_or_path, $callback->($statvfs)
169 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
170 aio_chown $fh_or_path, $uid, $gid, $callback->($status)
171 aio_chmod $fh_or_path, $mode, $callback->($status)
172 aio_truncate $fh_or_path, $offset, $callback->($status)
173 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
174 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
175 aio_unlink $pathname, $callback->($status)
176 aio_mknod $pathname, $mode, $dev, $callback->($status)
177 aio_link $srcpath, $dstpath, $callback->($status)
178 aio_symlink $srcpath, $dstpath, $callback->($status)
179 aio_readlink $pathname, $callback->($link)
180 aio_realpath $pathname, $callback->($path)
181 aio_rename $srcpath, $dstpath, $callback->($status)
182 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
183 aio_mkdir $pathname, $mode, $callback->($status)
184 aio_rmdir $pathname, $callback->($status)
185 aio_readdir $pathname, $callback->($entries)
186 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
187 IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
188 IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
189 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
190 aio_load $pathname, $data, $callback->($status)
191 aio_copy $srcpath, $dstpath, $callback->($status)
192 aio_move $srcpath, $dstpath, $callback->($status)
193 aio_rmtree $pathname, $callback->($status)
194 aio_fcntl $fh, $cmd, $arg, $callback->($status)
195 aio_ioctl $fh, $request, $buf, $callback->($status)
196 aio_sync $callback->($status)
197 aio_syncfs $fh, $callback->($status)
198 aio_fsync $fh, $callback->($status)
199 aio_fdatasync $fh, $callback->($status)
200 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
201 aio_pathsync $pathname, $callback->($status)
202 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status)
203 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
204 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
205 aio_mlockall $flags, $callback->($status)
206 aio_group $callback->(...)
207 aio_nop $callback->()
208
209 $prev_pri = aioreq_pri [$pri]
210 aioreq_nice $pri_adjust
211
212 IO::AIO::poll_wait
213 IO::AIO::poll_cb
214 IO::AIO::poll
215 IO::AIO::flush
216 IO::AIO::max_poll_reqs $nreqs
217 IO::AIO::max_poll_time $seconds
218 IO::AIO::min_parallel $nthreads
219 IO::AIO::max_parallel $nthreads
220 IO::AIO::max_idle $nthreads
221 IO::AIO::idle_timeout $seconds
222 IO::AIO::max_outstanding $maxreqs
223 IO::AIO::nreqs
224 IO::AIO::nready
225 IO::AIO::npending
226 IO::AIO::reinit
227
228 $nfd = IO::AIO::get_fdlimit
229 IO::AIO::min_fdlimit $nfd
230
231 IO::AIO::sendfile $ofh, $ifh, $offset, $count
232 IO::AIO::fadvise $fh, $offset, $len, $advice
233 IO::AIO::fexecve $fh, $argv, $envp
234
235 IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
236 IO::AIO::munmap $scalar
237 IO::AIO::mremap $scalar, $new_length, $flags[, $new_address]
238 IO::AIO::madvise $scalar, $offset, $length, $advice
239 IO::AIO::mprotect $scalar, $offset, $length, $protect
240 IO::AIO::munlock $scalar, $offset = 0, $length = undef
241 IO::AIO::munlockall
242
243 # stat extensions
244 $counter = IO::AIO::st_gen
245 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, IO::AIO::st_btime
246 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
247 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, IO::AIO::st_ctimensec, IO::AIO::st_btimensec
248 $seconds = IO::AIO::st_btimesec
249 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
250
251 # very much unportable syscalls
252 IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_len, $flags
253 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
254 IO::AIO::tee $r_fh, $w_fh, $length, $flags
255
256 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
257 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
258
259 $fh = IO::AIO::eventfd [$initval, [$flags]]
260 $fh = IO::AIO::memfd_create $pathname[, $flags]
261
262 $fh = IO::AIO::timerfd_create $clockid[, $flags]
263 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, $new_interval, $nbw_value
264 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
265
266 $fh = IO::AIO::pidfd_open $pid[, $flags]
267 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[, $flags]]
268 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
269
270 $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data = undef
271 $retval = IO::AIO::umount $path, $flags = 0
272
273 API NOTES
174 All the "aio_*" calls are more or less thin wrappers around the syscall 274 All the "aio_*" calls are more or less thin wrappers around the syscall
175 with the same name (sans "aio_"). The arguments are similar or 275 with the same name (sans "aio_"). The arguments are similar or
176 identical, and they all accept an additional (and optional) $callback 276 identical, and they all accept an additional (and optional) $callback
177 argument which must be a code reference. This code reference will get 277 argument which must be a code reference. This code reference will be
178 called with the syscall return code (e.g. most syscalls return -1 on
179 error, unlike perl, which usually delivers "false") as its sole argument
180 after the given syscall has been executed asynchronously. 278 called after the syscall has been executed in an asynchronous fashion.
279 The results of the request will be passed as arguments to the callback
280 (and, if an error occured, in $!) - for most requests the syscall return
281 code (e.g. most syscalls return -1 on error, unlike perl, which usually
282 delivers "false").
283
284 Some requests (such as "aio_readdir") pass the actual results and
285 communicate failures by passing "undef".
181 286
182 All functions expecting a filehandle keep a copy of the filehandle 287 All functions expecting a filehandle keep a copy of the filehandle
183 internally until the request has finished. 288 internally until the request has finished.
184 289
185 All functions return request objects of type IO::AIO::REQ that allow 290 All functions return request objects of type IO::AIO::REQ that allow
186 further manipulation of those requests while they are in-flight. 291 further manipulation of those requests while they are in-flight.
187 292
188 The pathnames you pass to these routines *must* be absolute and encoded 293 The pathnames you pass to these routines *should* be absolute. The
189 as octets. The reason for the former is that at the time the request is 294 reason for this is that at the time the request is being executed, the
190 being executed, the current working directory could have changed. 295 current working directory could have changed. Alternatively, you can
191 Alternatively, you can make sure that you never change the current 296 make sure that you never change the current working directory anywhere
192 working directory anywhere in the program and then use relative paths. 297 in the program and then use relative paths. You can also take advantage
298 of IO::AIOs working directory abstraction, that lets you specify paths
299 relative to some previously-opened "working directory object" - see the
300 description of the "IO::AIO::WD" class later in this document.
193 301
194 To encode pathnames as octets, either make sure you either: a) always 302 To encode pathnames as octets, either make sure you either: a) always
195 pass in filenames you got from outside (command line, readdir etc.) 303 pass in filenames you got from outside (command line, readdir etc.)
196 without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module 304 without tinkering, b) are in your native filesystem encoding, c) use the
197 and encode your pathnames to the locale (or other) encoding in effect in 305 Encode module and encode your pathnames to the locale (or other)
198 the user environment, d) use Glib::filename_from_unicode on unicode 306 encoding in effect in the user environment, d) use
199 filenames or e) use something else to ensure your scalar has the correct 307 Glib::filename_from_unicode on unicode filenames or e) use something
200 contents. 308 else to ensure your scalar has the correct contents.
201 309
202 This works, btw. independent of the internal UTF-8 bit, which IO::AIO 310 This works, btw. independent of the internal UTF-8 bit, which IO::AIO
203 handles correctly whether it is set or not. 311 handles correctly whether it is set or not.
204 312
313 AIO REQUEST FUNCTIONS
205 $prev_pri = aioreq_pri [$pri] 314 $prev_pri = aioreq_pri [$pri]
206 Returns the priority value that would be used for the next request 315 Returns the priority value that would be used for the next request
207 and, if $pri is given, sets the priority for the next aio request. 316 and, if $pri is given, sets the priority for the next aio request.
208 317
209 The default priority is 0, the minimum and maximum priorities are -4 318 The default priority is 0, the minimum and maximum priorities are -4
… …
231 Similar to "aioreq_pri", but subtracts the given value from the 340 Similar to "aioreq_pri", but subtracts the given value from the
232 current priority, so the effect is cumulative. 341 current priority, so the effect is cumulative.
233 342
234 aio_open $pathname, $flags, $mode, $callback->($fh) 343 aio_open $pathname, $flags, $mode, $callback->($fh)
235 Asynchronously open or create a file and call the callback with a 344 Asynchronously open or create a file and call the callback with a
236 newly created filehandle for the file. 345 newly created filehandle for the file (or "undef" in case of an
237 346 error).
238 The pathname passed to "aio_open" must be absolute. See API NOTES,
239 above, for an explanation.
240 347
241 The $flags argument is a bitmask. See the "Fcntl" module for a list. 348 The $flags argument is a bitmask. See the "Fcntl" module for a list.
242 They are the same as used by "sysopen". 349 They are the same as used by "sysopen".
243 350
244 Likewise, $mode specifies the mode of the newly created file, if it 351 Likewise, $mode specifies the mode of the newly created file, if it
… …
248 will be modified by the umask in effect then the request is being 355 will be modified by the umask in effect then the request is being
249 executed, so better never change the umask. 356 executed, so better never change the umask.
250 357
251 Example: 358 Example:
252 359
253 aio_open "/etc/passwd", O_RDONLY, 0, sub { 360 aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254 if ($_[0]) { 361 if ($_[0]) {
255 print "open successful, fh is $_[0]\n"; 362 print "open successful, fh is $_[0]\n";
256 ... 363 ...
257 } else { 364 } else {
258 die "open failed: $!\n"; 365 die "open failed: $!\n";
259 } 366 }
260 }; 367 };
261 368
369 In addition to all the common open modes/flags ("O_RDONLY",
370 "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
371 "O_APPEND"), the following POSIX and non-POSIX constants are
372 available (missing ones on your system are, as usual, 0):
373
374 "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
375 "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
376 "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT"
377 and "O_ACCMODE".
378
262 aio_close $fh, $callback->($status) 379 aio_close $fh, $callback->($status)
263 Asynchronously close a file and call the callback with the result 380 Asynchronously close a file and call the callback with the result
264 code. 381 code.
265 382
266 Unfortunately, you can't do this to perl. Perl *insists* very 383 Unfortunately, you can't do this to perl. Perl *insists* very
… …
271 will use dup2 to overwrite the file descriptor with the write-end of 388 will use dup2 to overwrite the file descriptor with the write-end of
272 a pipe (the pipe fd will be created on demand and will be cached). 389 a pipe (the pipe fd will be created on demand and will be cached).
273 390
274 Or in other words: the file descriptor will be closed, but it will 391 Or in other words: the file descriptor will be closed, but it will
275 not be free for reuse until the perl filehandle is closed. 392 not be free for reuse until the perl filehandle is closed.
393
394 aio_seek $fh, $offset, $whence, $callback->($offs)
395 Seeks the filehandle to the new $offset, similarly to perl's
396 "sysseek". The $whence can use the traditional values (0 for
397 "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
398 "IO::AIO::SEEK_END").
399
400 The resulting absolute offset will be passed to the callback, or -1
401 in case of an error.
402
403 In theory, the $whence constants could be different than the
404 corresponding values from Fcntl, but perl guarantees they are the
405 same, so don't panic.
406
407 As a GNU/Linux (and maybe Solaris) extension, also the constants
408 "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
409 could be found. No guarantees about suitability for use in
410 "aio_seek" or Perl's "sysseek" can be made though, although I would
411 naively assume they "just work".
276 412
277 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 413 aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
278 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) 414 aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279 Reads or writes $length bytes from or to the specified $fh and 415 Reads or writes $length bytes from or to the specified $fh and
280 $offset into the scalar given by $data and offset $dataoffset and 416 $offset into the scalar given by $data and offset $dataoffset and
281 calls the callback without the actual number of bytes read (or -1 on 417 calls the callback with the actual number of bytes transferred (or
282 error, just like the syscall). 418 -1 on error, just like the syscall).
283 419
284 "aio_read" will, like "sysread", shrink or grow the $data scalar to 420 "aio_read" will, like "sysread", shrink or grow the $data scalar to
285 offset plus the actual number of bytes read. 421 offset plus the actual number of bytes read.
286 422
287 If $offset is undefined, then the current file descriptor offset 423 If $offset is undefined, then the current file descriptor offset
… …
309 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 445 aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
310 Tries to copy $length bytes from $in_fh to $out_fh. It starts 446 Tries to copy $length bytes from $in_fh to $out_fh. It starts
311 reading at byte offset $in_offset, and starts writing at the current 447 reading at byte offset $in_offset, and starts writing at the current
312 file offset of $out_fh. Because of that, it is not safe to issue 448 file offset of $out_fh. Because of that, it is not safe to issue
313 more than one "aio_sendfile" per $out_fh, as they will interfere 449 more than one "aio_sendfile" per $out_fh, as they will interfere
314 with each other. 450 with each other. The same $in_fh works fine though, as this function
451 does not move or use the file offset of $in_fh.
315 452
453 Please note that "aio_sendfile" can read more bytes from $in_fh than
454 are written, and there is no way to find out how many more bytes
455 have been read from "aio_sendfile" alone, as "aio_sendfile" only
456 provides the number of bytes written to $out_fh. Only if the result
457 value equals $length one can assume that $length bytes have been
458 read.
459
460 Unlike with other "aio_" functions, it makes a lot of sense to use
461 "aio_sendfile" on non-blocking sockets, as long as one end
462 (typically the $in_fh) is a file - the file I/O will then be
463 asynchronous, while the socket I/O will be non-blocking. Note,
464 however, that you can run into a trap where "aio_sendfile" reads
465 some data with readahead, then fails to write all data, and when the
466 socket is ready the next time, the data in the cache is already
467 lost, forcing "aio_sendfile" to again hit the disk. Explicit
468 "aio_read" + "aio_write" let's you better control resource usage.
469
316 This call tries to make use of a native "sendfile" syscall to 470 This call tries to make use of a native "sendfile"-like syscall to
317 provide zero-copy operation. For this to work, $out_fh should refer 471 provide zero-copy operation. For this to work, $out_fh should refer
318 to a socket, and $in_fh should refer to mmap'able file. 472 to a socket, and $in_fh should refer to an mmap'able file.
319 473
320 If the native sendfile call fails or is not implemented, it will be 474 If a native sendfile cannot be found or it fails with "ENOSYS",
321 emulated, so you can call "aio_sendfile" on any type of filehandle 475 "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322 regardless of the limitations of the operating system. 476 "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
477 any type of filehandle regardless of the limitations of the
478 operating system.
323 479
324 Please note, however, that "aio_sendfile" can read more bytes from 480 As native sendfile syscalls (as practically any non-POSIX interface
325 $in_fh than are written, and there is no way to find out how many 481 hacked together in a hurry to improve benchmark numbers) tend to be
326 bytes have been read from "aio_sendfile" alone, as "aio_sendfile" 482 rather buggy on many systems, this implementation tries to work
327 only provides the number of bytes written to $out_fh. Only if the 483 around some known bugs in Linux and FreeBSD kernels (probably
328 result value equals $length one can assume that $length bytes have 484 others, too), but that might fail, so you really really should check
329 been read. 485 the return value of "aio_sendfile" - fewer bytes than expected might
486 have been transferred.
330 487
331 aio_readahead $fh,$offset,$length, $callback->($retval) 488 aio_readahead $fh,$offset,$length, $callback->($retval)
332 "aio_readahead" populates the page cache with data from a file so 489 "aio_readahead" populates the page cache with data from a file so
333 that subsequent reads from that file will not block on disk I/O. The 490 that subsequent reads from that file will not block on disk I/O. The
334 $offset argument specifies the starting point from which data is to 491 $offset argument specifies the starting point from which data is to
… …
337 to a page boundary and bytes are read up to the next page boundary 494 to a page boundary and bytes are read up to the next page boundary
338 greater than or equal to (off-set+length). "aio_readahead" does not 495 greater than or equal to (off-set+length). "aio_readahead" does not
339 read beyond the end of the file. The current file offset of the file 496 read beyond the end of the file. The current file offset of the file
340 is left unchanged. 497 is left unchanged.
341 498
342 If that syscall doesn't exist (likely if your OS isn't Linux) it 499 If that syscall doesn't exist (likely if your kernel isn't Linux) it
343 will be emulated by simply reading the data, which would have a 500 will be emulated by simply reading the data, which would have a
344 similar effect. 501 similar effect.
345 502
346 aio_stat $fh_or_path, $callback->($status) 503 aio_stat $fh_or_path, $callback->($status)
347 aio_lstat $fh, $callback->($status) 504 aio_lstat $fh, $callback->($status)
348 Works like perl's "stat" or "lstat" in void context. The callback 505 Works almost exactly like perl's "stat" or "lstat" in void context.
349 will be called after the stat and the results will be available 506 The callback will be called after the stat and the results will be
350 using "stat _" or "-s _" etc... 507 available using "stat _" or "-s _" and other tests (with the
351 508 exception of "-B" and "-T").
352 The pathname passed to "aio_stat" must be absolute. See API NOTES,
353 above, for an explanation.
354 509
355 Currently, the stats are always 64-bit-stats, i.e. instead of 510 Currently, the stats are always 64-bit-stats, i.e. instead of
356 returning an error when stat'ing a large file, the results will be 511 returning an error when stat'ing a large file, the results will be
357 silently truncated unless perl itself is compiled with large file 512 silently truncated unless perl itself is compiled with large file
358 support. 513 support.
359 514
515 To help interpret the mode and dev/rdev stat values, IO::AIO offers
516 the following constants and functions (if not implemented, the
517 constants will be 0 and the functions will either "croak" or fall
518 back on traditional behaviour).
519
520 "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
521 "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
522 "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
523
524 To access higher resolution stat timestamps, see "SUBSECOND STAT
525 TIME ACCESS".
526
360 Example: Print the length of /etc/passwd: 527 Example: Print the length of /etc/passwd:
361 528
362 aio_stat "/etc/passwd", sub { 529 aio_stat "/etc/passwd", sub {
363 $_[0] and die "stat failed: $!"; 530 $_[0] and die "stat failed: $!";
364 print "size is ", -s _, "\n"; 531 print "size is ", -s _, "\n";
365 }; 532 };
366 533
534 aio_statvfs $fh_or_path, $callback->($statvfs)
535 Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
536 whether a file handle or path was passed.
537
538 On success, the callback is passed a hash reference with the
539 following members: "bsize", "frsize", "blocks", "bfree", "bavail",
540 "files", "ffree", "favail", "fsid", "flag" and "namemax". On
541 failure, "undef" is passed.
542
543 The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
544 and "ST_NOSUID".
545
546 The following non-POSIX IO::AIO::ST_* flag masks are defined to
547 their correct value when available, or to 0 on systems that do not
548 support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
549 "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
550 "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
551
552 Example: stat "/wd" and dump out the data if successful.
553
554 aio_statvfs "/wd", sub {
555 my $f = $_[0]
556 or die "statvfs: $!";
557
558 use Data::Dumper;
559 say Dumper $f;
560 };
561
562 # result:
563 {
564 bsize => 1024,
565 bfree => 4333064312,
566 blocks => 10253828096,
567 files => 2050765568,
568 flag => 4096,
569 favail => 2042092649,
570 bavail => 4333064312,
571 ffree => 2042092649,
572 namemax => 255,
573 frsize => 1024,
574 fsid => 1810
575 }
576
367 aio_utime $fh_or_path, $atime, $mtime, $callback->($status) 577 aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
368 Works like perl's "utime" function (including the special case of 578 Works like perl's "utime" function (including the special case of
369 $atime and $mtime being undef). Fractional times are supported if 579 $atime and $mtime being undef). Fractional times are supported if
370 the underlying syscalls support them. 580 the underlying syscalls support them.
371 581
372 When called with a pathname, uses utimes(2) if available, otherwise 582 When called with a pathname, uses utimensat(2) or utimes(2) if
373 utime(2). If called on a file descriptor, uses futimes(2) if 583 available, otherwise utime(2). If called on a file descriptor, uses
374 available, otherwise returns ENOSYS, so this is not portable. 584 futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so
585 this is not portable.
375 586
376 Examples: 587 Examples:
377 588
378 # set atime and mtime to current time (basically touch(1)): 589 # set atime and mtime to current time (basically touch(1)):
379 aio_utime "path", undef, undef; 590 aio_utime "path", undef, undef;
… …
393 aio_chown "path", 0, undef; 604 aio_chown "path", 0, undef;
394 605
395 aio_truncate $fh_or_path, $offset, $callback->($status) 606 aio_truncate $fh_or_path, $offset, $callback->($status)
396 Works like truncate(2) or ftruncate(2). 607 Works like truncate(2) or ftruncate(2).
397 608
609 aio_allocate $fh, $mode, $offset, $len, $callback->($status)
610 Allocates or frees disk space according to the $mode argument. See
611 the linux "fallocate" documentation for details.
612
613 $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
614 space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE |
615 IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
616
617 IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
618 (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range,
619 "FALLOC_FL_INSERT_RANGE" to insert a range and
620 "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your
621 fallocate(2) manpage).
622
623 The file system block size used by "fallocate" is presumably the
624 "f_bsize" returned by "statvfs", but different filesystems and
625 filetypes can dictate other limitations.
626
627 If "fallocate" isn't available or cannot be emulated (currently no
628 emulation will be attempted), passes -1 and sets $! to "ENOSYS".
629
398 aio_chmod $fh_or_path, $mode, $callback->($status) 630 aio_chmod $fh_or_path, $mode, $callback->($status)
399 Works like perl's "chmod" function. 631 Works like perl's "chmod" function.
400 632
401 aio_unlink $pathname, $callback->($status) 633 aio_unlink $pathname, $callback->($status)
402 Asynchronously unlink (delete) a file and call the callback with the 634 Asynchronously unlink (delete) a file and call the callback with the
403 result code. 635 result code.
404 636
405 aio_mknod $path, $mode, $dev, $callback->($status) 637 aio_mknod $pathname, $mode, $dev, $callback->($status)
406 [EXPERIMENTAL] 638 [EXPERIMENTAL]
407 639
408 Asynchronously create a device node (or fifo). See mknod(2). 640 Asynchronously create a device node (or fifo). See mknod(2).
409 641
410 The only (POSIX-) portable way of calling this function is: 642 The only (POSIX-) portable way of calling this function is:
411 643
412 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... 644 aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ...
645
646 See "aio_stat" for info about some potentially helpful extra
647 constants and functions.
413 648
414 aio_link $srcpath, $dstpath, $callback->($status) 649 aio_link $srcpath, $dstpath, $callback->($status)
415 Asynchronously create a new link to the existing object at $srcpath 650 Asynchronously create a new link to the existing object at $srcpath
416 at the path $dstpath and call the callback with the result code. 651 at the path $dstpath and call the callback with the result code.
417 652
418 aio_symlink $srcpath, $dstpath, $callback->($status) 653 aio_symlink $srcpath, $dstpath, $callback->($status)
419 Asynchronously create a new symbolic link to the existing object at 654 Asynchronously create a new symbolic link to the existing object at
420 $srcpath at the path $dstpath and call the callback with the result 655 $srcpath at the path $dstpath and call the callback with the result
421 code. 656 code.
422 657
423 aio_readlink $path, $callback->($link) 658 aio_readlink $pathname, $callback->($link)
424 Asynchronously read the symlink specified by $path and pass it to 659 Asynchronously read the symlink specified by $path and pass it to
425 the callback. If an error occurs, nothing or undef gets passed to 660 the callback. If an error occurs, nothing or undef gets passed to
426 the callback. 661 the callback.
427 662
663 aio_realpath $pathname, $callback->($path)
664 Asynchronously make the path absolute and resolve any symlinks in
665 $path. The resulting path only consists of directories (same as
666 Cwd::realpath).
667
668 This request can be used to get the absolute path of the current
669 working directory by passing it a path of . (a single dot).
670
428 aio_rename $srcpath, $dstpath, $callback->($status) 671 aio_rename $srcpath, $dstpath, $callback->($status)
429 Asynchronously rename the object at $srcpath to $dstpath, just as 672 Asynchronously rename the object at $srcpath to $dstpath, just as
430 rename(2) and call the callback with the result code. 673 rename(2) and call the callback with the result code.
674
675 On systems that support the AIO::WD working directory abstraction
676 natively, the case "[$wd, "."]" as $srcpath is specialcased -
677 instead of failing, "rename" is called on the absolute path of $wd.
678
679 aio_rename2 $srcpath, $dstpath, $flags, $callback->($status)
680 Basically a version of "aio_rename" with an additional $flags
681 argument. Calling this with "$flags=0" is the same as calling
682 "aio_rename".
683
684 Non-zero flags are currently only supported on GNU/Linux systems
685 that support renameat2. Other systems fail with "ENOSYS" in this
686 case.
687
688 The following constants are available (missing ones are, as usual
689 0), see renameat2(2) for details:
690
691 "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and
692 "IO::AIO::RENAME_WHITEOUT".
431 693
432 aio_mkdir $pathname, $mode, $callback->($status) 694 aio_mkdir $pathname, $mode, $callback->($status)
433 Asynchronously mkdir (create) a directory and call the callback with 695 Asynchronously mkdir (create) a directory and call the callback with
434 the result code. $mode will be modified by the umask at the time the 696 the result code. $mode will be modified by the umask at the time the
435 request is executed, so do not change your umask. 697 request is executed, so do not change your umask.
436 698
437 aio_rmdir $pathname, $callback->($status) 699 aio_rmdir $pathname, $callback->($status)
438 Asynchronously rmdir (delete) a directory and call the callback with 700 Asynchronously rmdir (delete) a directory and call the callback with
439 the result code. 701 the result code.
440 702
703 On systems that support the AIO::WD working directory abstraction
704 natively, the case "[$wd, "."]" is specialcased - instead of
705 failing, "rmdir" is called on the absolute path of $wd.
706
441 aio_readdir $pathname, $callback->($entries) 707 aio_readdir $pathname, $callback->($entries)
442 Unlike the POSIX call of the same name, "aio_readdir" reads an 708 Unlike the POSIX call of the same name, "aio_readdir" reads an
443 entire directory (i.e. opendir + readdir + closedir). The entries 709 entire directory (i.e. opendir + readdir + closedir). The entries
444 will not be sorted, and will NOT include the "." and ".." entries. 710 will not be sorted, and will NOT include the "." and ".." entries.
445 711
446 The callback is passed a single argument which is either "undef" or 712 The callback is passed a single argument which is either "undef" or
447 an array-ref with the filenames. 713 an array-ref with the filenames.
448 714
449 aio_readdirx $pathname, $flags, $callback->($entries, $flags) 715 aio_readdirx $pathname, $flags, $callback->($entries, $flags)
450 Quite similar to "aio_readdir", but the $flags argument allows to 716 Quite similar to "aio_readdir", but the $flags argument allows one
451 tune behaviour and output format. In case of an error, $entries will 717 to tune behaviour and output format. In case of an error, $entries
452 be "undef". 718 will be "undef".
453 719
454 The flags are a combination of the following constants, ORed 720 The flags are a combination of the following constants, ORed
455 together (the flags will also be passed to the callback, possibly 721 together (the flags will also be passed to the callback, possibly
456 modified): 722 modified):
457 723
458 IO::AIO::READDIR_DENTS 724 IO::AIO::READDIR_DENTS
459 When this flag is off, then the callback gets an arrayref with 725 Normally the callback gets an arrayref consisting of names only
460 of names only (as with "aio_readdir"), otherwise it gets an 726 (as with "aio_readdir"). If this flag is set, then the callback
461 arrayref with "[$name, $type, $inode]" arrayrefs, each 727 gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
462 describing a single directory entry in more detail. 728 describing a single directory entry in more detail:
463 729
464 $name is the name of the entry. 730 $name is the name of the entry.
465 731
466 $type is one of the "IO::AIO::DT_xxx" constants: 732 $type is one of the "IO::AIO::DT_xxx" constants:
467 733
468 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", 734 "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
469 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", 735 "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
470 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". 736 "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
471 737
472 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If 738 "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
473 you need to know, you have to run stat yourself. Also, for speed 739 you need to know, you have to run stat yourself. Also, for
474 reasons, the $type scalars are read-only: you can not modify 740 speed/memory reasons, the $type scalars are read-only: you must
475 them. 741 not modify them.
476 742
477 $inode is the inode number (which might not be exact on systems 743 $inode is the inode number (which might not be exact on systems
478 with 64 bit inode numbers and 32 bit perls). This field has 744 with 64 bit inode numbers and 32 bit perls). This field has
479 unspecified content on systems that do not deliver the inode 745 unspecified content on systems that do not deliver the inode
480 information. 746 information.
481 747
482 IO::AIO::READDIR_DIRS_FIRST 748 IO::AIO::READDIR_DIRS_FIRST
483 When this flag is set, then the names will be returned in an 749 When this flag is set, then the names will be returned in an
484 order where likely directories come first. This is useful when 750 order where likely directories come first, in optimal stat
485 you need to quickly find directories, or you want to find all 751 order. This is useful when you need to quickly find directories,
486 directories while avoiding to stat() each entry. 752 or you want to find all directories while avoiding to stat()
753 each entry.
487 754
488 If the system returns type information in readdir, then this is 755 If the system returns type information in readdir, then this is
489 used to find directories directly. Otherwise, likely directories 756 used to find directories directly. Otherwise, likely directories
490 are files beginning with ".", or otherwise files with no dots, 757 are names beginning with ".", or otherwise names with no dots,
491 of which files with short names are tried first. 758 of which names with short names are tried first.
492 759
493 IO::AIO::READDIR_STAT_ORDER 760 IO::AIO::READDIR_STAT_ORDER
494 When this flag is set, then the names will be returned in an 761 When this flag is set, then the names will be returned in an
495 order suitable for stat()'ing each one. That is, when you plan 762 order suitable for stat()'ing each one. That is, when you plan
496 to stat() all files in the given directory, then the returned 763 to stat() most or all files in the given directory, then the
497 order will likely be fastest. 764 returned order will likely be faster.
498 765
499 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are 766 If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
500 specified, then the likely dirs come first, resulting in a less 767 specified, then the likely dirs come first, resulting in a less
501 optimal stat order. 768 optimal stat order for stat'ing all entries, but likely a more
769 optimal order for finding subdirectories.
502 770
503 IO::AIO::READDIR_FOUND_UNKNOWN 771 IO::AIO::READDIR_FOUND_UNKNOWN
504 This flag should not be set when calling "aio_readdirx". 772 This flag should not be set when calling "aio_readdirx".
505 Instead, it is being set by "aio_readdirx", when any of the 773 Instead, it is being set by "aio_readdirx", when any of the
506 $type's found were "IO::AIO::DT_UNKNOWN". The absense of this 774 $type's found were "IO::AIO::DT_UNKNOWN". The absence of this
507 flag therefore indicates that all $type's are known, which can 775 flag therefore indicates that all $type's are known, which can
508 be used to speed up some algorithms. 776 be used to speed up some algorithms.
509 777
778 aio_slurp $pathname, $offset, $length, $data, $callback->($status)
779 Opens, reads and closes the given file. The data is put into $data,
780 which is resized as required.
781
782 If $offset is negative, then it is counted from the end of the file.
783
784 If $length is zero, then the remaining length of the file is used.
785 Also, in this case, the same limitations to modifying $data apply as
786 when IO::AIO::mmap is used, i.e. it must only be modified in-place
787 with "substr". If the size of the file is known, specifying a
788 non-zero $length results in a performance advantage.
789
790 This request is similar to the older "aio_load" request, but since
791 it is a single request, it might be more efficient to use.
792
793 Example: load /etc/passwd into $passwd.
794
795 my $passwd;
796 aio_slurp "/etc/passwd", 0, 0, $passwd, sub {
797 $_[0] >= 0
798 or die "/etc/passwd: $!\n";
799
800 printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd;
801 print $passwd;
802 };
803 IO::AIO::flush;
804
510 aio_load $path, $data, $callback->($status) 805 aio_load $pathname, $data, $callback->($status)
511 This is a composite request that tries to fully load the given file 806 This is a composite request that tries to fully load the given file
512 into memory. Status is the same as with aio_read. 807 into memory. Status is the same as with aio_read.
808
809 Using "aio_slurp" might be more efficient, as it is a single
810 request.
513 811
514 aio_copy $srcpath, $dstpath, $callback->($status) 812 aio_copy $srcpath, $dstpath, $callback->($status)
515 Try to copy the *file* (directories not supported as either source 813 Try to copy the *file* (directories not supported as either source
516 or destination) from $srcpath to $dstpath and call the callback with 814 or destination) from $srcpath to $dstpath and call the callback with
517 the 0 (error) or -1 ok. 815 a status of 0 (ok) or -1 (error, see $!).
816
817 Existing destination files will be truncated.
518 818
519 This is a composite request that creates the destination file with 819 This is a composite request that creates the destination file with
520 mode 0200 and copies the contents of the source file into it using 820 mode 0200 and copies the contents of the source file into it using
521 "aio_sendfile", followed by restoring atime, mtime, access mode and 821 "aio_sendfile", followed by restoring atime, mtime, access mode and
522 uid/gid, in that order. 822 uid/gid, in that order.
… …
526 uid/gid, where errors are being ignored. 826 uid/gid, where errors are being ignored.
527 827
528 aio_move $srcpath, $dstpath, $callback->($status) 828 aio_move $srcpath, $dstpath, $callback->($status)
529 Try to move the *file* (directories not supported as either source 829 Try to move the *file* (directories not supported as either source
530 or destination) from $srcpath to $dstpath and call the callback with 830 or destination) from $srcpath to $dstpath and call the callback with
531 the 0 (error) or -1 ok. 831 a status of 0 (ok) or -1 (error, see $!).
532 832
533 This is a composite request that tries to rename(2) the file first; 833 This is a composite request that tries to rename(2) the file first;
534 if rename fails with "EXDEV", it copies the file with "aio_copy" 834 if rename fails with "EXDEV", it copies the file with "aio_copy"
535 and, if that is successful, unlinks the $srcpath. 835 and, if that is successful, unlinks the $srcpath.
536 836
537 aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 837 aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
538 Scans a directory (similar to "aio_readdir") but additionally tries 838 Scans a directory (similar to "aio_readdir") but additionally tries
539 to efficiently separate the entries of directory $path into two sets 839 to efficiently separate the entries of directory $path into two sets
540 of names, directories you can recurse into (directories), and ones 840 of names, directories you can recurse into (directories), and ones
541 you cannot recurse into (everything else, including symlinks to 841 you cannot recurse into (everything else, including symlinks to
542 directories). 842 directories).
543 843
544 "aio_scandir" is a composite request that creates of many sub 844 "aio_scandir" is a composite request that generates many sub
545 requests_ $maxreq specifies the maximum number of outstanding aio 845 requests. $maxreq specifies the maximum number of outstanding aio
546 requests that this function generates. If it is "<= 0", then a 846 requests that this function generates. If it is "<= 0", then a
547 suitable default will be chosen (currently 4). 847 suitable default will be chosen (currently 4).
548 848
549 On error, the callback is called without arguments, otherwise it 849 On error, the callback is called without arguments, otherwise it
550 receives two array-refs with path-relative entry names. 850 receives two array-refs with path-relative entry names.
… …
557 print "everything else: @$nondirs\n"; 857 print "everything else: @$nondirs\n";
558 }; 858 };
559 859
560 Implementation notes. 860 Implementation notes.
561 861
562 The "aio_readdir" cannot be avoided, but "stat()"'ing every entry 862 The "aio_readdir" cannot be avoided, but stat()'ing every entry can.
563 can.
564 863
565 If readdir returns file type information, then this is used directly 864 If readdir returns file type information, then this is used directly
566 to find directories. 865 to find directories.
567 866
568 Otherwise, after reading the directory, the modification time, size 867 Otherwise, after reading the directory, the modification time, size
… …
575 Then entries will be sorted into likely directories a non-initial 874 Then entries will be sorted into likely directories a non-initial
576 dot currently) and likely non-directories (see "aio_readdirx"). Then 875 dot currently) and likely non-directories (see "aio_readdirx"). Then
577 every entry plus an appended "/." will be "stat"'ed, likely 876 every entry plus an appended "/." will be "stat"'ed, likely
578 directories first, in order of their inode numbers. If that 877 directories first, in order of their inode numbers. If that
579 succeeds, it assumes that the entry is a directory or a symlink to 878 succeeds, it assumes that the entry is a directory or a symlink to
580 directory (which will be checked seperately). This is often faster 879 directory (which will be checked separately). This is often faster
581 than stat'ing the entry itself because filesystems might detect the 880 than stat'ing the entry itself because filesystems might detect the
582 type of the entry without reading the inode data (e.g. ext2fs 881 type of the entry without reading the inode data (e.g. ext2fs
583 filetype feature), even on systems that cannot return the filetype 882 filetype feature), even on systems that cannot return the filetype
584 information on readdir. 883 information on readdir.
585 884
… …
591 890
592 It will also likely work on non-POSIX filesystems with reduced 891 It will also likely work on non-POSIX filesystems with reduced
593 efficiency as those tend to return 0 or 1 as link counts, which 892 efficiency as those tend to return 0 or 1 as link counts, which
594 disables the directory counting heuristic. 893 disables the directory counting heuristic.
595 894
596 aio_rmtree $path, $callback->($status) 895 aio_rmtree $pathname, $callback->($status)
597 Delete a directory tree starting (and including) $path, return the 896 Delete a directory tree starting (and including) $path, return the
598 status of the final "rmdir" only. This is a composite request that 897 status of the final "rmdir" only. This is a composite request that
599 uses "aio_scandir" to recurse into and rmdir directories, and unlink 898 uses "aio_scandir" to recurse into and rmdir directories, and unlink
600 everything else. 899 everything else.
601 900
901 aio_fcntl $fh, $cmd, $arg, $callback->($status)
902 aio_ioctl $fh, $request, $buf, $callback->($status)
903 These work just like the "fcntl" and "ioctl" built-in functions,
904 except they execute asynchronously and pass the return value to the
905 callback.
906
907 Both calls can be used for a lot of things, some of which make more
908 sense to run asynchronously in their own thread, while some others
909 make less sense. For example, calls that block waiting for external
910 events, such as locking, will also lock down an I/O thread while it
911 is waiting, which can deadlock the whole I/O system. At the same
912 time, there might be no alternative to using a thread to wait.
913
914 So in general, you should only use these calls for things that do
915 (filesystem) I/O, not for things that wait for other events
916 (network, other processes), although if you are careful and know
917 what you are doing, you still can.
918
919 The following constants are available and can be used for normal
920 "ioctl" and "fcntl" as well (missing ones are, as usual 0):
921
922 "F_DUPFD_CLOEXEC",
923
924 "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW",
925
926 "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE",
927 "FIDEDUPERANGE".
928
929 "F_ADD_SEALS", "F_GET_SEALS", "F_SEAL_SEAL", "F_SEAL_SHRINK",
930 "F_SEAL_GROW" and "F_SEAL_WRITE".
931
932 "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION",
933 "FS_IOC_SETVERSION", "FS_IOC_FIEMAP".
934
935 "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR",
936 "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT",
937 "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE".
938
939 "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL",
940 "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL",
941 "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL",
942 "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL",
943 "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE".
944
945 "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE",
946 "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME",
947 "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT",
948 "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT",
949 "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX",
950 "FS_XFLAG_HASATTR",
951
952 "BLKROSET", "BLKROGET", "BLKRRPART", "BLKGETSIZE", "BLKFLSBUF",
953 "BLKRASET", "BLKRAGET", "BLKFRASET", "BLKFRAGET", "BLKSECTSET",
954 "BLKSECTGET", "BLKSSZGET", "BLKBSZGET", "BLKBSZSET", "BLKGETSIZE64",
955
602 aio_sync $callback->($status) 956 aio_sync $callback->($status)
603 Asynchronously call sync and call the callback when finished. 957 Asynchronously call sync and call the callback when finished.
604 958
605 aio_fsync $fh, $callback->($status) 959 aio_fsync $fh, $callback->($status)
606 Asynchronously call fsync on the given filehandle and call the 960 Asynchronously call fsync on the given filehandle and call the
… …
610 Asynchronously call fdatasync on the given filehandle and call the 964 Asynchronously call fdatasync on the given filehandle and call the
611 callback with the fdatasync result code. 965 callback with the fdatasync result code.
612 966
613 If this call isn't available because your OS lacks it or it couldn't 967 If this call isn't available because your OS lacks it or it couldn't
614 be detected, it will be emulated by calling "fsync" instead. 968 be detected, it will be emulated by calling "fsync" instead.
969
970 aio_syncfs $fh, $callback->($status)
971 Asynchronously call the syncfs syscall to sync the filesystem
972 associated to the given filehandle and call the callback with the
973 syncfs result code. If syncfs is not available, calls sync(), but
974 returns -1 and sets errno to "ENOSYS" nevertheless.
615 975
616 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) 976 aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
617 Sync the data portion of the file specified by $offset and $length 977 Sync the data portion of the file specified by $offset and $length
618 to disk (but NOT the metadata), by calling the Linux-specific 978 to disk (but NOT the metadata), by calling the Linux-specific
619 sync_file_range call. If sync_file_range is not available or it 979 sync_file_range call. If sync_file_range is not available or it
… …
623 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", 983 "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
624 "IO::AIO::SYNC_FILE_RANGE_WRITE" and 984 "IO::AIO::SYNC_FILE_RANGE_WRITE" and
625 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range 985 "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
626 manpage for details. 986 manpage for details.
627 987
628 aio_pathsync $path, $callback->($status) 988 aio_pathsync $pathname, $callback->($status)
629 This request tries to open, fsync and close the given path. This is 989 This request tries to open, fsync and close the given path. This is
630 a composite request intended to sync directories after directory 990 a composite request intended to sync directories after directory
631 operations (E.g. rename). This might not work on all operating 991 operations (E.g. rename). This might not work on all operating
632 systems or have any specific effect, but usually it makes sure that 992 systems or have any specific effect, but usually it makes sure that
633 directory changes get written to disc. It works for anything that 993 directory changes get written to disc. It works for anything that
… …
636 Future versions of this function might fall back to other methods 996 Future versions of this function might fall back to other methods
637 when "fsync" on the directory fails (such as calling "sync"). 997 when "fsync" on the directory fails (such as calling "sync").
638 998
639 Passes 0 when everything went ok, and -1 on error. 999 Passes 0 when everything went ok, and -1 on error.
640 1000
1001 aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC,
1002 $callback->($status)
1003 This is a rather advanced IO::AIO call, which only works on
1004 mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
1005 also works on data scalars managed by the Sys::Mmap or Mmap modules,
1006 note that the scalar must only be modified in-place while an aio
1007 operation is pending on it).
1008
1009 It calls the "msync" function of your OS, if available, with the
1010 memory area starting at $offset in the string and ending $length
1011 bytes later. If $length is negative, counts from the end, and if
1012 $length is "undef", then it goes till the end of the string. The
1013 flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus
1014 an optional "IO::AIO::MS_INVALIDATE".
1015
1016 aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
1017 $callback->($status)
1018 This is a rather advanced IO::AIO call, which works best on
1019 mmap(2)ed scalars.
1020
1021 It touches (reads or writes) all memory pages in the specified range
1022 inside the scalar. All caveats and parameters are the same as for
1023 "aio_msync", above, except for flags, which must be either 0 (which
1024 reads all pages and ensures they are instantiated) or
1025 "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
1026 and writing an octet from it, which dirties the page).
1027
1028 aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
1029 This is a rather advanced IO::AIO call, which works best on
1030 mmap(2)ed scalars.
1031
1032 It reads in all the pages of the underlying storage into memory (if
1033 any) and locks them, so they are not getting swapped/paged out or
1034 removed.
1035
1036 If $length is undefined, then the scalar will be locked till the
1037 end.
1038
1039 On systems that do not implement "mlock", this function returns -1
1040 and sets errno to "ENOSYS".
1041
1042 Note that the corresponding "munlock" is synchronous and is
1043 documented under "MISCELLANEOUS FUNCTIONS".
1044
1045 Example: open a file, mmap and mlock it - both will be undone when
1046 $data gets destroyed.
1047
1048 open my $fh, "<", $path or die "$path: $!";
1049 my $data;
1050 IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
1051 aio_mlock $data; # mlock in background
1052
1053 aio_mlockall $flags, $callback->($status)
1054 Calls the "mlockall" function with the given $flags (a combination
1055 of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and
1056 "IO::AIO::MCL_ONFAULT").
1057
1058 On systems that do not implement "mlockall", this function returns
1059 -1 and sets errno to "ENOSYS". Similarly, flag combinations not
1060 supported by the system result in a return value of -1 with errno
1061 being set to "EINVAL".
1062
1063 Note that the corresponding "munlockall" is synchronous and is
1064 documented under "MISCELLANEOUS FUNCTIONS".
1065
1066 Example: asynchronously lock all current and future pages into
1067 memory.
1068
1069 aio_mlockall IO::AIO::MCL_FUTURE;
1070
1071 aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
1072 Queries the extents of the given file (by calling the Linux "FIEMAP"
1073 ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
1074 details). If the ioctl is not available on your OS, then this
1075 request will fail with "ENOSYS".
1076
1077 $start is the starting offset to query extents for, $length is the
1078 size of the range to query - if it is "undef", then the whole file
1079 will be queried.
1080
1081 $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
1082 "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
1083 also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
1084 query the data portion.
1085
1086 $count is the maximum number of extent records to return. If it is
1087 "undef", then IO::AIO queries all extents of the range. As a very
1088 special case, if it is 0, then the callback receives the number of
1089 extents instead of the extents themselves (which is unreliable, see
1090 below).
1091
1092 If an error occurs, the callback receives no arguments. The special
1093 "errno" value "IO::AIO::EBADR" is available to test for flag errors.
1094
1095 Otherwise, the callback receives an array reference with extent
1096 structures. Each extent structure is an array reference itself, with
1097 the following members:
1098
1099 [$logical, $physical, $length, $flags]
1100
1101 Flags is any combination of the following flag values (typically
1102 either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
1103
1104 "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
1105 "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
1106 "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
1107 "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
1108 "IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
1109 "IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
1110 "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
1111 or "IO::AIO::FIEMAP_EXTENT_SHARED".
1112
1113 At the time of this writing (Linux 3.2), this request is unreliable
1114 unless $count is "undef", as the kernel has all sorts of bugs
1115 preventing it to return all extents of a range for files with a
1116 large number of extents. The code (only) works around all these
1117 issues if $count is "undef".
1118
641 aio_group $callback->(...) 1119 aio_group $callback->(...)
642 This is a very special aio request: Instead of doing something, it 1120 This is a very special aio request: Instead of doing something, it
643 is a container for other aio requests, which is useful if you want 1121 is a container for other aio requests, which is useful if you want
644 to bundle many requests into a single, composite, request with a 1122 to bundle many requests into a single, composite, request with a
645 definite callback and the ability to cancel the whole request with 1123 definite callback and the ability to cancel the whole request with
… …
678 While it is theoretically handy to have simple I/O scheduling 1156 While it is theoretically handy to have simple I/O scheduling
679 requests like sleep and file handle readable/writable, the overhead 1157 requests like sleep and file handle readable/writable, the overhead
680 this creates is immense (it blocks a thread for a long time) so do 1158 this creates is immense (it blocks a thread for a long time) so do
681 not use this function except to put your application under 1159 not use this function except to put your application under
682 artificial I/O pressure. 1160 artificial I/O pressure.
1161
1162 IO::AIO::WD - multiple working directories
1163 Your process only has one current working directory, which is used by
1164 all threads. This makes it hard to use relative paths (some other
1165 component could call "chdir" at any time, and it is hard to control when
1166 the path will be used by IO::AIO).
1167
1168 One solution for this is to always use absolute paths. This usually
1169 works, but can be quite slow (the kernel has to walk the whole path on
1170 every access), and can also be a hassle to implement.
1171
1172 Newer POSIX systems have a number of functions (openat, fdopendir,
1173 futimensat and so on) that make it possible to specify working
1174 directories per operation.
1175
1176 For portability, and because the clowns who "designed", or shall I
1177 write, perpetrated this new interface were obviously half-drunk, this
1178 abstraction cannot be perfect, though.
1179
1180 IO::AIO allows you to convert directory paths into a so-called
1181 IO::AIO::WD object. This object stores the canonicalised, absolute
1182 version of the path, and on systems that allow it, also a directory file
1183 descriptor.
1184
1185 Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
1186 or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
1187 object and a pathname instead (or the IO::AIO::WD object alone, which
1188 gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
1189 IO::AIO::WD object is ignored, otherwise the pathname is resolved
1190 relative to that IO::AIO::WD object.
1191
1192 For example, to get a wd object for /etc and then stat passwd inside,
1193 you would write:
1194
1195 aio_wd "/etc", sub {
1196 my $etcdir = shift;
1197
1198 # although $etcdir can be undef on error, there is generally no reason
1199 # to check for errors here, as aio_stat will fail with ENOENT
1200 # when $etcdir is undef.
1201
1202 aio_stat [$etcdir, "passwd"], sub {
1203 # yay
1204 };
1205 };
1206
1207 The fact that "aio_wd" is a request and not a normal function shows that
1208 creating an IO::AIO::WD object is itself a potentially blocking
1209 operation, which is why it is done asynchronously.
1210
1211 To stat the directory obtained with "aio_wd" above, one could write
1212 either of the following three request calls:
1213
1214 aio_lstat "/etc" , sub { ... # pathname as normal string
1215 aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
1216 aio_lstat $wd , sub { ... # shorthand for the previous
1217
1218 As with normal pathnames, IO::AIO keeps a copy of the working directory
1219 object and the pathname string, so you could write the following without
1220 causing any issues due to $path getting reused:
1221
1222 my $path = [$wd, undef];
1223
1224 for my $name (qw(abc def ghi)) {
1225 $path->[1] = $name;
1226 aio_stat $path, sub {
1227 # ...
1228 };
1229 }
1230
1231 There are some caveats: when directories get renamed (or deleted), the
1232 pathname string doesn't change, so will point to the new directory (or
1233 nowhere at all), while the directory fd, if available on the system,
1234 will still point to the original directory. Most functions accepting a
1235 pathname will use the directory fd on newer systems, and the string on
1236 older systems. Some functions (such as "aio_realpath") will always rely
1237 on the string form of the pathname.
1238
1239 So this functionality is mainly useful to get some protection against
1240 "chdir", to easily get an absolute path out of a relative path for
1241 future reference, and to speed up doing many operations in the same
1242 directory (e.g. when stat'ing all files in a directory).
1243
1244 The following functions implement this working directory abstraction:
1245
1246 aio_wd $pathname, $callback->($wd)
1247 Asynchonously canonicalise the given pathname and convert it to an
1248 IO::AIO::WD object representing it. If possible and supported on the
1249 system, also open a directory fd to speed up pathname resolution
1250 relative to this working directory.
1251
1252 If something goes wrong, then "undef" is passwd to the callback
1253 instead of a working directory object and $! is set appropriately.
1254 Since passing "undef" as working directory component of a pathname
1255 fails the request with "ENOENT", there is often no need for error
1256 checking in the "aio_wd" callback, as future requests using the
1257 value will fail in the expected way.
1258
1259 IO::AIO::CWD
1260 This is a compile time constant (object) that represents the process
1261 current working directory.
1262
1263 Specifying this object as working directory object for a pathname is
1264 as if the pathname would be specified directly, without a directory
1265 object. For example, these calls are functionally identical:
1266
1267 aio_stat "somefile", sub { ... };
1268 aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
1269
1270 To recover the path associated with an IO::AIO::WD object, you can use
1271 "aio_realpath":
1272
1273 aio_realpath $wd, sub {
1274 warn "path is $_[0]\n";
1275 };
1276
1277 Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
1278 sometimes, fall back to using an absolue path.
683 1279
684 IO::AIO::REQ CLASS 1280 IO::AIO::REQ CLASS
685 All non-aggregate "aio_*" functions return an object of this class when 1281 All non-aggregate "aio_*" functions return an object of this class when
686 called in non-void context. 1282 called in non-void context.
687 1283
… …
761 $grp->cancel_subs 1357 $grp->cancel_subs
762 Cancel all subrequests and clears any feeder, but not the group 1358 Cancel all subrequests and clears any feeder, but not the group
763 request itself. Useful when you queued a lot of events but got a 1359 request itself. Useful when you queued a lot of events but got a
764 result early. 1360 result early.
765 1361
1362 The group request will finish normally (you cannot add requests to
1363 the group).
1364
766 $grp->result (...) 1365 $grp->result (...)
767 Set the result value(s) that will be passed to the group callback 1366 Set the result value(s) that will be passed to the group callback
768 when all subrequests have finished and set the groups errno to the 1367 when all subrequests have finished and set the groups errno to the
769 current value of errno (just like calling "errno" without an error 1368 current value of errno (just like calling "errno" without an error
770 number). By default, no argument will be passed and errno is zero. 1369 number). By default, no argument will be passed and errno is zero.
… …
784 Sets a feeder/generator on this group: every group can have an 1383 Sets a feeder/generator on this group: every group can have an
785 attached generator that generates requests if idle. The idea behind 1384 attached generator that generates requests if idle. The idea behind
786 this is that, although you could just queue as many requests as you 1385 this is that, although you could just queue as many requests as you
787 want in a group, this might starve other requests for a potentially 1386 want in a group, this might starve other requests for a potentially
788 long time. For example, "aio_scandir" might generate hundreds of 1387 long time. For example, "aio_scandir" might generate hundreds of
789 thousands "aio_stat" requests, delaying any later requests for a 1388 thousands of "aio_stat" requests, delaying any later requests for a
790 long time. 1389 long time.
791 1390
792 To avoid this, and allow incremental generation of requests, you can 1391 To avoid this, and allow incremental generation of requests, you can
793 instead a group and set a feeder on it that generates those 1392 instead a group and set a feeder on it that generates those
794 requests. The feed callback will be called whenever there are few 1393 requests. The feed callback will be called whenever there are few
… …
836 results. 1435 results.
837 1436
838 See "poll_cb" for an example. 1437 See "poll_cb" for an example.
839 1438
840 IO::AIO::poll_cb 1439 IO::AIO::poll_cb
841 Process some outstanding events on the result pipe. You have to call 1440 Process some requests that have reached the result phase (i.e. they
842 this regularly. Returns 0 if all events could be processed, or -1 if 1441 have been executed but the results are not yet reported). You have
843 it returned earlier for whatever reason. Returns immediately when no 1442 to call this "regularly" to finish outstanding requests.
844 events are outstanding. The amount of events processed depends on
845 the settings of "IO::AIO::max_poll_req" and
846 "IO::AIO::max_poll_time".
847 1443
1444 Returns 0 if all events could be processed (or there were no events
1445 to process), or -1 if it returned earlier for whatever reason.
1446 Returns immediately when no events are outstanding. The amount of
1447 events processed depends on the settings of "IO::AIO::max_poll_req",
1448 "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
1449
848 If not all requests were processed for whatever reason, the 1450 If not all requests were processed for whatever reason, the poll
849 filehandle will still be ready when "poll_cb" returns, so normally 1451 file descriptor will still be ready when "poll_cb" returns, so
850 you don't have to do anything special to have it called later. 1452 normally you don't have to do anything special to have it called
1453 later.
1454
1455 Apart from calling "IO::AIO::poll_cb" when the event filehandle
1456 becomes ready, it can be beneficial to call this function from loops
1457 which submit a lot of requests, to make sure the results get
1458 processed when they become available and not just when the loop is
1459 finished and the event loop takes over again. This function returns
1460 very fast when there are no outstanding requests.
851 1461
852 Example: Install an Event watcher that automatically calls 1462 Example: Install an Event watcher that automatically calls
853 IO::AIO::poll_cb with high priority (more examples can be found in 1463 IO::AIO::poll_cb with high priority (more examples can be found in
854 the SYNOPSIS section, at the top of this document): 1464 the SYNOPSIS section, at the top of this document):
855 1465
856 Event->io (fd => IO::AIO::poll_fileno, 1466 Event->io (fd => IO::AIO::poll_fileno,
857 poll => 'r', async => 1, 1467 poll => 'r', async => 1,
858 cb => \&IO::AIO::poll_cb); 1468 cb => \&IO::AIO::poll_cb);
1469
1470 IO::AIO::poll_wait
1471 Wait until either at least one request is in the result phase or no
1472 requests are outstanding anymore.
1473
1474 This is useful if you want to synchronously wait for some requests
1475 to become ready, without actually handling them.
1476
1477 See "nreqs" for an example.
1478
1479 IO::AIO::poll
1480 Waits until some requests have been handled.
1481
1482 Returns the number of requests processed, but is otherwise strictly
1483 equivalent to:
1484
1485 IO::AIO::poll_wait, IO::AIO::poll_cb
1486
1487 IO::AIO::flush
1488 Wait till all outstanding AIO requests have been handled.
1489
1490 Strictly equivalent to:
1491
1492 IO::AIO::poll_wait, IO::AIO::poll_cb
1493 while IO::AIO::nreqs;
1494
1495 This function can be useful at program aborts, to make sure
1496 outstanding I/O has been done ("IO::AIO" uses an "END" block which
1497 already calls this function on normal exits), or when you are merely
1498 using "IO::AIO" for its more advanced functions, rather than for
1499 async I/O, e.g.:
1500
1501 my ($dirs, $nondirs);
1502 IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ };
1503 IO::AIO::flush;
1504 # $dirs, $nondirs are now set
859 1505
860 IO::AIO::max_poll_reqs $nreqs 1506 IO::AIO::max_poll_reqs $nreqs
861 IO::AIO::max_poll_time $seconds 1507 IO::AIO::max_poll_time $seconds
862 These set the maximum number of requests (default 0, meaning 1508 These set the maximum number of requests (default 0, meaning
863 infinity) that are being processed by "IO::AIO::poll_cb" in one 1509 infinity) that are being processed by "IO::AIO::poll_cb" in one
… …
887 # use a low priority so other tasks have priority 1533 # use a low priority so other tasks have priority
888 Event->io (fd => IO::AIO::poll_fileno, 1534 Event->io (fd => IO::AIO::poll_fileno,
889 poll => 'r', nice => 1, 1535 poll => 'r', nice => 1,
890 cb => &IO::AIO::poll_cb); 1536 cb => &IO::AIO::poll_cb);
891 1537
892 IO::AIO::poll_wait
893 If there are any outstanding requests and none of them in the result
894 phase, wait till the result filehandle becomes ready for reading
895 (simply does a "select" on the filehandle. This is useful if you
896 want to synchronously wait for some requests to finish).
897
898 See "nreqs" for an example.
899
900 IO::AIO::poll
901 Waits until some requests have been handled.
902
903 Returns the number of requests processed, but is otherwise strictly
904 equivalent to:
905
906 IO::AIO::poll_wait, IO::AIO::poll_cb
907
908 IO::AIO::flush
909 Wait till all outstanding AIO requests have been handled.
910
911 Strictly equivalent to:
912
913 IO::AIO::poll_wait, IO::AIO::poll_cb
914 while IO::AIO::nreqs;
915
916 CONTROLLING THE NUMBER OF THREADS 1538 CONTROLLING THE NUMBER OF THREADS
917 IO::AIO::min_parallel $nthreads 1539 IO::AIO::min_parallel $nthreads
918 Set the minimum number of AIO threads to $nthreads. The current 1540 Set the minimum number of AIO threads to $nthreads. The current
919 default is 8, which means eight asynchronous operations can execute 1541 default is 8, which means eight asynchronous operations can execute
920 concurrently at any one time (the number of outstanding requests, 1542 concurrently at any one time (the number of outstanding requests,
… …
949 1571
950 Under normal circumstances you don't need to call this function. 1572 Under normal circumstances you don't need to call this function.
951 1573
952 IO::AIO::max_idle $nthreads 1574 IO::AIO::max_idle $nthreads
953 Limit the number of threads (default: 4) that are allowed to idle 1575 Limit the number of threads (default: 4) that are allowed to idle
954 (i.e., threads that did not get a request to process within 10 1576 (i.e., threads that did not get a request to process within the idle
955 seconds). That means if a thread becomes idle while $nthreads other 1577 timeout (default: 10 seconds). That means if a thread becomes idle
956 threads are also idle, it will free its resources and exit. 1578 while $nthreads other threads are also idle, it will free its
1579 resources and exit.
957 1580
958 This is useful when you allow a large number of threads (e.g. 100 or 1581 This is useful when you allow a large number of threads (e.g. 100 or
959 1000) to allow for extremely high load situations, but want to free 1582 1000) to allow for extremely high load situations, but want to free
960 resources under normal circumstances (1000 threads can easily 1583 resources under normal circumstances (1000 threads can easily
961 consume 30MB of RAM). 1584 consume 30MB of RAM).
962 1585
963 The default is probably ok in most situations, especially if thread 1586 The default is probably ok in most situations, especially if thread
964 creation is fast. If thread creation is very slow on your system you 1587 creation is fast. If thread creation is very slow on your system you
965 might want to use larger values. 1588 might want to use larger values.
966 1589
1590 IO::AIO::idle_timeout $seconds
1591 Sets the minimum idle timeout (default 10) after which worker
1592 threads are allowed to exit. SEe "IO::AIO::max_idle".
1593
967 IO::AIO::max_outstanding $maxreqs 1594 IO::AIO::max_outstanding $maxreqs
968 This is a very bad function to use in interactive programs because
969 it blocks, and a bad way to reduce concurrency because it is
970 inexact: Better use an "aio_group" together with a feed callback.
971
972 Sets the maximum number of outstanding requests to $nreqs. If you do 1595 Sets the maximum number of outstanding requests to $nreqs. If you do
973 queue up more than this number of requests, the next call to the 1596 queue up more than this number of requests, the next call to
974 "poll_cb" (and "poll_some" and other functions calling "poll_cb") 1597 "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
975 function will block until the limit is no longer exceeded. 1598 "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
1599 no longer exceeded.
976 1600
977 The default value is very large, so there is no practical limit on 1601 In other words, this setting does not enforce a queue limit, but can
1602 be used to make poll functions block if the limit is exceeded.
1603
1604 This is a bad function to use in interactive programs because it
1605 blocks, and a bad way to reduce concurrency because it is inexact.
1606 If you need to issue many requests without being able to call a poll
1607 function on demand, it is better to use an "aio_group" together with
1608 a feed callback.
1609
1610 Its main use is in scripts without an event loop - when you want to
1611 stat a lot of files, you can write something like this:
1612
1613 IO::AIO::max_outstanding 32;
1614
1615 for my $path (...) {
1616 aio_stat $path , ...;
1617 IO::AIO::poll_cb;
1618 }
1619
1620 IO::AIO::flush;
1621
1622 The call to "poll_cb" inside the loop will normally return
1623 instantly, allowing the loop to progress, but as soon as more than
1624 32 requests are in-flight, it will block until some requests have
1625 been handled. This keeps the loop from pushing a large number of
1626 "aio_stat" requests onto the queue (which, with many paths to stat,
1627 can use up a lot of memory).
1628
1629 The default value for "max_outstanding" is very large, so there is
978 the number of outstanding requests. 1630 no practical limit on the number of outstanding requests.
979
980 You can still queue as many requests as you want. Therefore,
981 "max_outstanding" is mainly useful in simple scripts (with low
982 values) or as a stop gap to shield against fatal memory overflow
983 (with large values).
984 1631
985 STATISTICAL INFORMATION 1632 STATISTICAL INFORMATION
986 IO::AIO::nreqs 1633 IO::AIO::nreqs
987 Returns the number of requests currently in the ready, execute or 1634 Returns the number of requests currently in the ready, execute or
988 pending states (i.e. for which their callback has not been invoked 1635 pending states (i.e. for which their callback has not been invoked
… …
999 1646
1000 IO::AIO::npending 1647 IO::AIO::npending
1001 Returns the number of requests currently in the pending state 1648 Returns the number of requests currently in the pending state
1002 (executed, but not yet processed by poll_cb). 1649 (executed, but not yet processed by poll_cb).
1003 1650
1651 SUBSECOND STAT TIME ACCESS
1652 Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can
1653 generally find access/modification and change times with subsecond time
1654 accuracy of the system supports it, but perl's built-in functions only
1655 return the integer part.
1656
1657 The following functions return the timestamps of the most recent stat
1658 with subsecond precision on most systems and work both after
1659 "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return
1660 value is only meaningful after a successful "stat"/"lstat" call, or
1661 during/after a successful "aio_stat"/"aio_lstat" callback.
1662
1663 This is similar to the Time::HiRes "stat" functions, but can return full
1664 resolution without rounding and work with standard perl "stat",
1665 alleviating the need to call the special "Time::HiRes" functions, which
1666 do not act like their perl counterparts.
1667
1668 On operating systems or file systems where subsecond time resolution is
1669 not supported or could not be detected, a fractional part of 0 is
1670 returned, so it is always safe to call these functions.
1671
1672 $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime,
1673 IO::AIO::st_btime
1674 Return the access, modication, change or birth time, respectively,
1675 including fractional part. Due to the limited precision of floating
1676 point, the accuracy on most platforms is only a bit better than
1677 milliseconds for times around now - see the *nsec* function family,
1678 below, for full accuracy.
1679
1680 File birth time is only available when the OS and perl support it
1681 (on FreeBSD and NetBSD at the time of this writing, although support
1682 is adaptive, so if your OS/perl gains support, IO::AIO can take
1683 advantage of it). On systems where it isn't available, 0 is
1684 currently returned, but this might change to "undef" in a future
1685 version.
1686
1687 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime
1688 Returns access, modification, change and birth time all in one go,
1689 and maybe more times in the future version.
1690
1691 $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec,
1692 IO::AIO::st_ctimensec, IO::AIO::st_btimensec
1693 Return the fractional access, modifcation, change or birth time, in
1694 nanoseconds, as an integer in the range 0 to 999999999.
1695
1696 Note that no accessors are provided for access, modification and
1697 change times - you need to get those from "stat _" if required ("int
1698 IO::AIO::st_atime" and so on will *not* generally give you the
1699 correct value).
1700
1701 $seconds = IO::AIO::st_btimesec
1702 The (integral) seconds part of the file birth time, if available.
1703
1704 ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec
1705 Like the functions above, but returns all four times in one go (and
1706 maybe more in future versions).
1707
1708 $counter = IO::AIO::st_gen
1709 Returns the generation counter (in practice this is just a random
1710 number) of the file. This is only available on platforms which have
1711 this member in their "struct stat" (most BSDs at the time of this
1712 writing) and generally only to the root usert. If unsupported, 0 is
1713 returned, but this might change to "undef" in a future version.
1714
1715 Example: print the high resolution modification time of /etc, using
1716 "stat", and "IO::AIO::aio_stat".
1717
1718 if (stat "/etc") {
1719 printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime;
1720 }
1721
1722 IO::AIO::aio_stat "/etc", sub {
1723 $_[0]
1724 and return;
1725
1726 printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec;
1727 };
1728
1729 IO::AIO::flush;
1730
1731 Output of the awbove on my system, showing reduced and full accuracy:
1732
1733 stat(/etc) mtime: 1534043702.020808
1734 aio_stat(/etc) mtime: 1534043702.020807792
1735
1004 MISCELLANEOUS FUNCTIONS 1736 MISCELLANEOUS FUNCTIONS
1005 IO::AIO implements some functions that might be useful, but are not 1737 IO::AIO implements some functions that are useful when you want to use
1006 asynchronous. 1738 some "Advanced I/O" function not available to in Perl, without going the
1739 "Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
1740 counterpart.
1741
1742 $retval = IO::AIO::fexecve $fh, $argv, $envp
1743 A more-or-less direct equivalent to the POSIX "fexecve" functions,
1744 which allows you to specify the program to be executed via a file
1745 descriptor (or handle). Returns -1 and sets errno to "ENOSYS" if not
1746 available.
1747
1748 $retval = IO::AIO::mount $special, $path, $fstype, $flags = 0, $data =
1749 undef
1750 Calls the GNU/Linux mount syscall with the given arguments. All
1751 except $flags are strings, and if $data is "undef", a "NULL" will be
1752 passed.
1753
1754 The following values for $flags are available:
1755
1756 "IO::AIO::MS_RDONLY", "IO::AIO::MS_NOSUID", "IO::AIO::MS_NODEV",
1757 "IO::AIO::MS_NOEXEC", "IO::AIO::MS_SYNCHRONOUS",
1758 "IO::AIO::MS_REMOUNT", "IO::AIO::MS_MANDLOCK",
1759 "IO::AIO::MS_DIRSYNC", "IO::AIO::MS_NOATIME",
1760 "IO::AIO::MS_NODIRATIME", "IO::AIO::MS_BIND", "IO::AIO::MS_MOVE",
1761 "IO::AIO::MS_REC", "IO::AIO::MS_SILENT", "IO::AIO::MS_POSIXACL",
1762 "IO::AIO::MS_UNBINDABLE", "IO::AIO::MS_PRIVATE",
1763 "IO::AIO::MS_SLAVE", "IO::AIO::MS_SHARED", "IO::AIO::MS_RELATIME",
1764 "IO::AIO::MS_KERNMOUNT", "IO::AIO::MS_I_VERSION",
1765 "IO::AIO::MS_STRICTATIME", "IO::AIO::MS_LAZYTIME",
1766 "IO::AIO::MS_ACTIVE", "IO::AIO::MS_NOUSER", "IO::AIO::MS_RMT_MASK",
1767 "IO::AIO::MS_MGC_VAL" and "IO::AIO::MS_MGC_MSK".
1768
1769 $retval = IO::AIO::umount $path, $flags = 0
1770 Invokes the GNU/Linux "umount" or "umount2" syscalls. Always calls
1771 "umount" if $flags is 0, otherwqise always tries to call "umount2".
1772
1773 The following $flags are available:
1774
1775 "IO::AIO::MNT_FORCE", "IO::AIO::MNT_DETACH", "IO::AIO::MNT_EXPIRE"
1776 and "IO::AIO::UMOUNT_NOFOLLOW".
1777
1778 $numfd = IO::AIO::get_fdlimit
1779 Tries to find the current file descriptor limit and returns it, or
1780 "undef" and sets $! in case of an error. The limit is one larger
1781 than the highest valid file descriptor number.
1782
1783 IO::AIO::min_fdlimit [$numfd]
1784 Try to increase the current file descriptor limit(s) to at least
1785 $numfd by changing the soft or hard file descriptor resource limit.
1786 If $numfd is missing, it will try to set a very high limit, although
1787 this is not recommended when you know the actual minimum that you
1788 require.
1789
1790 If the limit cannot be raised enough, the function makes a
1791 best-effort attempt to increase the limit as much as possible, using
1792 various tricks, while still failing. You can query the resulting
1793 limit using "IO::AIO::get_fdlimit".
1794
1795 If an error occurs, returns "undef" and sets $!, otherwise returns
1796 true.
1007 1797
1008 IO::AIO::sendfile $ofh, $ifh, $offset, $count 1798 IO::AIO::sendfile $ofh, $ifh, $offset, $count
1009 Calls the "eio_sendfile_sync" function, which is like 1799 Calls the "eio_sendfile_sync" function, which is like
1010 "aio_sendfile", but is blocking (this makes most sense if you know 1800 "aio_sendfile", but is blocking (this makes most sense if you know
1011 the input data is likely cached already and the output filehandle is 1801 the input data is likely cached already and the output filehandle is
1012 set to non-blocking operations). 1802 set to non-blocking operations).
1013 1803
1014 Returns the number of bytes copied, or -1 on error. 1804 Returns the number of bytes copied, or -1 on error.
1015 1805
1016 IO::AIO::fadvise $fh, $offset, $len, $advice 1806 IO::AIO::fadvise $fh, $offset, $len, $advice
1017 Simply calls the "posix_fadvise" function (see it's manpage for 1807 Simply calls the "posix_fadvise" function (see its manpage for
1018 details). The following advice constants are avaiable: 1808 details). The following advice constants are available:
1019 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", 1809 "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1020 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", 1810 "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1021 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". 1811 "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1022 1812
1023 On systems that do not implement "posix_fadvise", this function 1813 On systems that do not implement "posix_fadvise", this function
1024 returns ENOSYS, otherwise the return value of "posix_fadvise". 1814 returns ENOSYS, otherwise the return value of "posix_fadvise".
1025 1815
1816 IO::AIO::madvise $scalar, $offset, $len, $advice
1817 Simply calls the "posix_madvise" function (see its manpage for
1818 details). The following advice constants are available:
1819 "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
1820 "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
1821 "IO::AIO::MADV_DONTNEED".
1822
1823 If $offset is negative, counts from the end. If $length is negative,
1824 the remaining length of the $scalar is used. If possible, $length
1825 will be reduced to fit into the $scalar.
1826
1827 On systems that do not implement "posix_madvise", this function
1828 returns ENOSYS, otherwise the return value of "posix_madvise".
1829
1830 IO::AIO::mprotect $scalar, $offset, $len, $protect
1831 Simply calls the "mprotect" function on the preferably AIO::mmap'ed
1832 $scalar (see its manpage for details). The following protect
1833 constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
1834 "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
1835
1836 If $offset is negative, counts from the end. If $length is negative,
1837 the remaining length of the $scalar is used. If possible, $length
1838 will be reduced to fit into the $scalar.
1839
1840 On systems that do not implement "mprotect", this function returns
1841 ENOSYS, otherwise the return value of "mprotect".
1842
1843 IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1844 Memory-maps a file (or anonymous memory range) and attaches it to
1845 the given $scalar, which will act like a string scalar. Returns true
1846 on success, and false otherwise.
1847
1848 The scalar must exist, but its contents do not matter - this means
1849 you cannot use a nonexistant array or hash element. When in doubt,
1850 "undef" the scalar first.
1851
1852 The only operations allowed on the mmapped scalar are
1853 "substr"/"vec", which don't change the string length, and most
1854 read-only operations such as copying it or searching it with regexes
1855 and so on.
1856
1857 Anything else is unsafe and will, at best, result in memory leaks.
1858
1859 The memory map associated with the $scalar is automatically removed
1860 when the $scalar is undef'd or destroyed, or when the
1861 "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it.
1862
1863 This calls the "mmap"(2) function internally. See your system's
1864 manual page for details on the $length, $prot and $flags parameters.
1865
1866 The $length must be larger than zero and smaller than the actual
1867 filesize.
1868
1869 $prot is a combination of "IO::AIO::PROT_NONE",
1870 "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1871 "IO::AIO::PROT_WRITE",
1872
1873 $flags can be a combination of "IO::AIO::MAP_SHARED" or
1874 "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1875 not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1876 "MAP_ANON" if your system only provides this constant),
1877 "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1878 "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
1879 "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1880 "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_STACK",
1881 "IO::AIO::MAP_FIXED_NOREPLACE", "IO::AIO::MAP_SHARED_VALIDATE",
1882 "IO::AIO::MAP_SYNC" or "IO::AIO::MAP_UNINITIALIZED".
1883
1884 If $fh is "undef", then a file descriptor of -1 is passed.
1885
1886 $offset is the offset from the start of the file - it generally must
1887 be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
1888
1889 Example:
1890
1891 use Digest::MD5;
1892 use IO::AIO;
1893
1894 open my $fh, "<verybigfile"
1895 or die "$!";
1896
1897 IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
1898 or die "verybigfile: $!";
1899
1900 my $fast_md5 = md5 $data;
1901
1902 IO::AIO::munmap $scalar
1903 Removes a previous mmap and undefines the $scalar.
1904
1905 IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[,
1906 $new_address = 0]
1907 Calls the Linux-specific mremap(2) system call. The $scalar must
1908 have been mapped by "IO::AIO::mmap", and $flags must currently
1909 either be 0 or "IO::AIO::MREMAP_MAYMOVE".
1910
1911 Returns true if successful, and false otherwise. If the underlying
1912 mmapped region has changed address, then the true value has the
1913 numerical value 1, otherwise it has the numerical value 0:
1914
1915 my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE
1916 or die "mremap: $!";
1917
1918 if ($success*1) {
1919 warn "scalar has chanegd address in memory\n";
1920 }
1921
1922 "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently
1923 implemented, but not supported and might go away in a future
1924 version.
1925
1926 On systems where this call is not supported or is not emulated, this
1927 call returns falls and sets $! to "ENOSYS".
1928
1929 IO::AIO::mlockall $flags
1930 Calls the "eio_mlockall_sync" function, which is like
1931 "aio_mlockall", but is blocking.
1932
1933 IO::AIO::munlock $scalar, $offset = 0, $length = undef
1934 Calls the "munlock" function, undoing the effects of a previous
1935 "aio_mlock" call (see its description for details).
1936
1937 IO::AIO::munlockall
1938 Calls the "munlockall" function.
1939
1940 On systems that do not implement "munlockall", this function returns
1941 ENOSYS, otherwise the return value of "munlockall".
1942
1943 $fh = IO::AIO::accept4 $r_fh, $sockaddr, $sockaddr_maxlen, $flags
1944 Uses the GNU/Linux accept4(2) syscall, if available, to accept a
1945 socket and return the new file handle on success, or sets $! and
1946 returns "undef" on error.
1947
1948 The remote name of the new socket will be stored in $sockaddr, which
1949 will be extended to allow for at least $sockaddr_maxlen octets. If
1950 the socket name does not fit into $sockaddr_maxlen octets, this is
1951 signaled by returning a longer string in $sockaddr, which might or
1952 might not be truncated.
1953
1954 To accept name-less sockets, use "undef" for $sockaddr and 0 for
1955 $sockaddr_maxlen.
1956
1957 The main reasons to use this syscall rather than portable accept(2)
1958 are that you can specify "SOCK_NONBLOCK" and/or "SOCK_CLOEXEC" flags
1959 and you can accept name-less sockets by specifying 0 for
1960 $sockaddr_maxlen, which is sadly not possible with perl's interface
1961 to "accept".
1962
1963 IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
1964 Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
1965 $w_off are "undef", then "NULL" is passed for these, otherwise they
1966 should be the file offset.
1967
1968 $r_fh and $w_fh should not refer to the same file, as splice might
1969 silently corrupt the data in this case.
1970
1971 The following symbol flag values are available:
1972 "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
1973 "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
1974
1975 See the splice(2) manpage for details.
1976
1977 IO::AIO::tee $r_fh, $w_fh, $length, $flags
1978 Calls the GNU/Linux tee(2) syscall, see its manpage and the
1979 description for "IO::AIO::splice" above for details.
1980
1981 $actual_size = IO::AIO::pipesize $r_fh[, $new_size]
1982 Attempts to query or change the pipe buffer size. Obviously works
1983 only on pipes, and currently works only on GNU/Linux systems, and
1984 fails with -1/"ENOSYS" everywhere else. If anybody knows how to
1985 influence pipe buffer size on other systems, drop me a note.
1986
1987 ($rfh, $wfh) = IO::AIO::pipe2 [$flags]
1988 This is a direct interface to the Linux pipe2(2) system call. If
1989 $flags is missing or 0, then this should be the same as a call to
1990 perl's built-in "pipe" function and create a new pipe, and works on
1991 systems that lack the pipe2 syscall. On win32, this case invokes
1992 "_pipe (..., 4096, O_BINARY)".
1993
1994 If $flags is non-zero, it tries to invoke the pipe2 system call with
1995 the given flags (Linux 2.6.27, glibc 2.9).
1996
1997 On success, the read and write file handles are returned.
1998
1999 On error, nothing will be returned. If the pipe2 syscall is missing
2000 and $flags is non-zero, fails with "ENOSYS".
2001
2002 Please refer to pipe2(2) for more info on the $flags, but at the
2003 time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
2004 and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
2005 supported.
2006
2007 Example: create a pipe race-free w.r.t. threads and fork:
2008
2009 my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC
2010 or die "pipe2: $!\n";
2011
2012 $fh = IO::AIO::memfd_create $pathname[, $flags]
2013 This is a direct interface to the Linux memfd_create(2) system call.
2014 The (unhelpful) default for $flags is 0, but your default should be
2015 "IO::AIO::MFD_CLOEXEC".
2016
2017 On success, the new memfd filehandle is returned, otherwise returns
2018 "undef". If the memfd_create syscall is missing, fails with
2019 "ENOSYS".
2020
2021 Please refer to memfd_create(2) for more info on this call.
2022
2023 The following $flags values are available: "IO::AIO::MFD_CLOEXEC",
2024 "IO::AIO::MFD_ALLOW_SEALING", "IO::AIO::MFD_HUGETLB",
2025 "IO::AIO::MFD_HUGETLB_2MB" and "IO::AIO::MFD_HUGETLB_1GB".
2026
2027 Example: create a new memfd.
2028
2029 my $fh = IO::AIO::memfd_create "somenameforprocfd", IO::AIO::MFD_CLOEXEC
2030 or die "memfd_create: $!\n";
2031
2032 $fh = IO::AIO::pidfd_open $pid[, $flags]
2033 This is an interface to the Linux pidfd_open(2) system call. The
2034 default for $flags is 0.
2035
2036 On success, a new pidfd filehandle is returned (that is already set
2037 to close-on-exec), otherwise returns "undef". If the syscall is
2038 missing, fails with "ENOSYS".
2039
2040 Example: open pid 6341 as pidfd.
2041
2042 my $fh = IO::AIO::pidfd_open 6341
2043 or die "pidfd_open: $!\n";
2044
2045 $status = IO::AIO::pidfd_send_signal $pidfh, $signal[, $siginfo[,
2046 $flags]]
2047 This is an interface to the Linux pidfd_send_signal system call. The
2048 default for $siginfo is "undef" and the default for $flags is 0.
2049
2050 Returns the system call status. If the syscall is missing, fails
2051 with "ENOSYS".
2052
2053 When specified, $siginfo must be a reference to a hash with one or
2054 more of the following members:
2055
2056 code - the "si_code" member
2057 pid - the "si_pid" member
2058 uid - the "si_uid" member
2059 value_int - the "si_value.sival_int" member
2060 value_ptr - the "si_value.sival_ptr" member, specified as an integer
2061
2062 Example: send a SIGKILL to the specified process.
2063
2064 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, undef
2065 and die "pidfd_send_signal: $!\n";
2066
2067 Example: send a SIGKILL to the specified process with extra data.
2068
2069 my $status = IO::AIO::pidfd_send_signal $pidfh, 9, { code => -1, value_int => 7 }
2070 and die "pidfd_send_signal: $!\n";
2071
2072 $fh = IO::AIO::pidfd_getfd $pidfh, $targetfd[, $flags]
2073 This is an interface to the Linux pidfd_getfd system call. The
2074 default for $flags is 0.
2075
2076 On success, returns a dup'ed copy of the target file descriptor
2077 (specified as an integer) returned (that is already set to
2078 close-on-exec), otherwise returns "undef". If the syscall is
2079 missing, fails with "ENOSYS".
2080
2081 Example: get a copy of standard error of another process and print
2082 soemthing to it.
2083
2084 my $errfh = IO::AIO::pidfd_getfd $pidfh, 2
2085 or die "pidfd_getfd: $!\n";
2086 print $errfh "stderr\n";
2087
2088 $fh = IO::AIO::eventfd [$initval, [$flags]]
2089 This is a direct interface to the Linux eventfd(2) system call. The
2090 (unhelpful) defaults for $initval and $flags are 0 for both.
2091
2092 On success, the new eventfd filehandle is returned, otherwise
2093 returns "undef". If the eventfd syscall is missing, fails with
2094 "ENOSYS".
2095
2096 Please refer to eventfd(2) for more info on this call.
2097
2098 The following symbol flag values are available:
2099 "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and
2100 "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30).
2101
2102 Example: create a new eventfd filehandle:
2103
2104 $fh = IO::AIO::eventfd 0, IO::AIO::EFD_CLOEXEC
2105 or die "eventfd: $!\n";
2106
2107 $fh = IO::AIO::timerfd_create $clockid[, $flags]
2108 This is a direct interface to the Linux timerfd_create(2) system
2109 call. The (unhelpful) default for $flags is 0, but your default
2110 should be "IO::AIO::TFD_CLOEXEC".
2111
2112 On success, the new timerfd filehandle is returned, otherwise
2113 returns "undef". If the timerfd_create syscall is missing, fails
2114 with "ENOSYS".
2115
2116 Please refer to timerfd_create(2) for more info on this call.
2117
2118 The following $clockid values are available:
2119 "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC"
2120 "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15)
2121 "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and
2122 "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11).
2123
2124 The following $flags values are available (Linux 2.6.27):
2125 "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC".
2126
2127 Example: create a new timerfd and set it to one-second repeated
2128 alarms, then wait for two alarms:
2129
2130 my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC
2131 or die "timerfd_create: $!\n";
2132
2133 defined IO::AIO::timerfd_settime $fh, 0, 1, 1
2134 or die "timerfd_settime: $!\n";
2135
2136 for (1..2) {
2137 8 == sysread $fh, my $buf, 8
2138 or die "timerfd read failure\n";
2139
2140 printf "number of expirations (likely 1): %d\n",
2141 unpack "Q", $buf;
2142 }
2143
2144 ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags,
2145 $new_interval, $nbw_value
2146 This is a direct interface to the Linux timerfd_settime(2) system
2147 call. Please refer to its manpage for more info on this call.
2148
2149 The new itimerspec is specified using two (possibly fractional)
2150 second values, $new_interval and $new_value).
2151
2152 On success, the current interval and value are returned (as per
2153 "timerfd_gettime"). On failure, the empty list is returned.
2154
2155 The following $flags values are available:
2156 "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET".
2157
2158 See "IO::AIO::timerfd_create" for a full example.
2159
2160 ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh
2161 This is a direct interface to the Linux timerfd_gettime(2) system
2162 call. Please refer to its manpage for more info on this call.
2163
2164 On success, returns the current values of interval and value for the
2165 given timerfd (as potentially fractional second values). On failure,
2166 the empty list is returned.
2167
2168EVENT LOOP INTEGRATION
2169 It is recommended to use AnyEvent::AIO to integrate IO::AIO
2170 automatically into many event loops:
2171
2172 # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
2173 use AnyEvent::AIO;
2174
2175 You can also integrate IO::AIO manually into many event loops, here are
2176 some examples of how to do this:
2177
2178 # EV integration
2179 my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
2180
2181 # Event integration
2182 Event->io (fd => IO::AIO::poll_fileno,
2183 poll => 'r',
2184 cb => \&IO::AIO::poll_cb);
2185
2186 # Glib/Gtk2 integration
2187 add_watch Glib::IO IO::AIO::poll_fileno,
2188 in => sub { IO::AIO::poll_cb; 1 };
2189
2190 # Tk integration
2191 Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
2192 readable => \&IO::AIO::poll_cb);
2193
2194 # Danga::Socket integration
2195 Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
2196 \&IO::AIO::poll_cb);
2197
1026 FORK BEHAVIOUR 2198 FORK BEHAVIOUR
1027 This module should do "the right thing" when the process using it forks: 2199 Usage of pthreads in a program changes the semantics of fork
2200 considerably. Specifically, only async-safe functions can be called
2201 after fork. Perl doesn't know about this, so in general, you cannot call
2202 fork with defined behaviour in perl if pthreads are involved. IO::AIO
2203 uses pthreads, so this applies, but many other extensions and (for
2204 inexplicable reasons) perl itself often is linked against pthreads, so
2205 this limitation applies to quite a lot of perls.
1028 2206
1029 Before the fork, IO::AIO enters a quiescent state where no requests can 2207 This module no longer tries to fight your OS, or POSIX. That means
1030 be added in other threads and no results will be processed. After the 2208 IO::AIO only works in the process that loaded it. Forking is fully
1031 fork the parent simply leaves the quiescent state and continues 2209 supported, but using IO::AIO in the child is not.
1032 request/result processing, while the child frees the request/result
1033 queue (so that the requests started before the fork will only be handled
1034 in the parent). Threads will be started on demand until the limit set in
1035 the parent process has been reached again.
1036 2210
1037 In short: the parent will, after a short pause, continue as if fork had 2211 You might get around by not *using* IO::AIO before (or after) forking.
1038 not been called, while the child will act as if IO::AIO has not been 2212 You could also try to call the IO::AIO::reinit function in the child:
1039 used yet. 2213
2214 IO::AIO::reinit
2215 Abandons all current requests and I/O threads and simply
2216 reinitialises all data structures. This is not an operation
2217 supported by any standards, but happens to work on GNU/Linux and
2218 some newer BSD systems.
2219
2220 The only reasonable use for this function is to call it after
2221 forking, if "IO::AIO" was used in the parent. Calling it while
2222 IO::AIO is active in the process will result in undefined behaviour.
2223 Calling it at any time will also result in any undefined (by POSIX)
2224 behaviour.
2225
2226 LINUX-SPECIFIC CALLS
2227 When a call is documented as "linux-specific" then this means it
2228 originated on GNU/Linux. "IO::AIO" will usually try to autodetect the
2229 availability and compatibility of such calls regardless of the platform
2230 it is compiled on, so platforms such as FreeBSD which often implement
2231 these calls will work. When in doubt, call them and see if they fail wth
2232 "ENOSYS".
1040 2233
1041 MEMORY USAGE 2234 MEMORY USAGE
1042 Per-request usage: 2235 Per-request usage:
1043 2236
1044 Each aio request uses - depending on your architecture - around 100-200 2237 Each aio request uses - depending on your architecture - around 100-200
… …
1055 In the execution phase, some aio requests require more memory for 2248 In the execution phase, some aio requests require more memory for
1056 temporary buffers, and each thread requires a stack and other data 2249 temporary buffers, and each thread requires a stack and other data
1057 structures (usually around 16k-128k, depending on the OS). 2250 structures (usually around 16k-128k, depending on the OS).
1058 2251
1059KNOWN BUGS 2252KNOWN BUGS
1060 Known bugs will be fixed in the next release. 2253 Known bugs will be fixed in the next release :)
2254
2255KNOWN ISSUES
2256 Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap"
2257 or "IO::AIO::aio_slurp") do not work with generic lvalues, such as
2258 non-created hash slots or other scalars I didn't think of. It's best to
2259 avoid such and either use scalar variables or making sure that the
2260 scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied).
2261
2262 I am not sure anything can be done about this, so this is considered a
2263 known issue, rather than a bug.
1061 2264
1062SEE ALSO 2265SEE ALSO
1063 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a 2266 AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
1064 more natural syntax. 2267 more natural syntax and IO::FDPass for file descriptor passing.
1065 2268
1066AUTHOR 2269AUTHOR
1067 Marc Lehmann <schmorp@schmorp.de> 2270 Marc Lehmann <schmorp@schmorp.de>
1068 http://home.schmorp.de/ 2271 http://home.schmorp.de/
1069 2272

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